What antibiotic to prescribe for a patient with sinus infection and anaphylaxis to Bactrim (trimethoprim/sulfamethoxazole) and penicillin?

Antibiotic Selection for Sinus Infection with Anaphylaxis to Bactrim and Penicillin

For a 55-year-old patient with sinus infection and anaphylaxis to both Bactrim and penicillin, prescribe a respiratory fluoroquinolone—either levofloxacin 500 mg once daily for 10 days or moxifloxacin 400 mg once daily for 10 days. 1, 2

Primary Recommendation: Respiratory Fluoroquinolones

Respiratory fluoroquinolones (levofloxacin or moxifloxacin) are the first-line choice for patients with true penicillin allergy (anaphylaxis) and acute bacterial rhinosinusitis. 1, 2 These agents provide:

• Excellent coverage against both Streptococcus pneumoniae (including penicillin-resistant strains) and Haemophilus influenzae 1, 2
• 90-92% predicted clinical efficacy for acute bacterial sinusitis 3
• Proven effectiveness in clinical trials with clinical success rates of 91.4% at 5 days and 88.6% at 10 days 4

Specific Dosing Options:

• Levofloxacin 500 mg orally once daily for 10-14 days 1, 2, 4
• Moxifloxacin 400 mg orally once daily for 10 days 1, 2

Why Not Other Options?

Cephalosporins Are Contraindicated

Cephalosporins (cefpodoxime, cefuroxime, cefdinir) should be avoided in patients with anaphylaxis to penicillin due to potential cross-reactivity. 2 While cephalosporins are appropriate for non-type I hypersensitivity reactions (e.g., rash), they carry a 1-10% cross-reactivity risk with true IgE-mediated penicillin allergy. 1

Macrolides Are Inadequate

Macrolides (azithromycin, clarithromycin, erythromycin) are not recommended as first-line therapy due to high resistance rates. 1, 3 The United States has:

• 40% macrolide-resistant S. pneumoniae 1

• Predicted clinical efficacy of only 78% and bacteriologic efficacy of 76% 1
• Weak activity against penicillin-resistant H. influenzae 3

Despite FDA approval of azithromycin 500 mg daily for 3 days for acute bacterial sinusitis 5, the high resistance rates make this a poor choice when better alternatives exist.

Trimethoprim-Sulfamethoxazole Is Already Excluded

The patient has anaphylaxis to Bactrim (trimethoprim-sulfamethoxazole), eliminating this option. Additionally, resistance rates are high: 50% for S. pneumoniae and 27% for H. influenzae. 1

Doxycycline Is a Weaker Alternative

Doxycycline is mentioned as an alternative for penicillin-allergic patients 1, 2, but it provides inferior coverage compared to fluoroquinolones and should be reserved for mild disease when fluoroquinolones are contraindicated.

Treatment Duration and Monitoring

• Standard duration is 10-14 days 1, 3
• Expect clinical improvement within 3-5 days 1, 3
• Reassess if symptoms worsen or fail to improve by 7 days 1

Critical Pitfalls to Avoid

Do not use cephalosporins in patients with anaphylaxis history. 2 The cross-reactivity risk is unacceptable when safer alternatives exist.

Do not prescribe macrolides as first-line therapy. 1, 3 The >40% resistance rate in the U.S. makes treatment failure likely.

Reserve fluoroquinolones appropriately but use them when indicated. 2, 3 While fluoroquinolone stewardship is important, this patient with dual anaphylaxis has a clear indication for their use.

Adjunctive Therapies

• Intranasal corticosteroids are helpful as adjunctive therapy 2, 3
• Supportive measures: adequate hydration, analgesics, warm facial packs, steamy showers, sleeping with head elevated 1, 3
• Saline irrigation improves sinus drainage 3

When to Refer

Refer to ENT specialist if:

• Patient fails to respond to fluoroquinolone therapy 3
• Recurrent sinusitis (≥3 episodes per year) 1, 3
• Complications such as orbital or intracranial involvement 3
• Severe symptoms with high fever or evidence of systemic toxicity 1